Molecular biology is the branch of biology that concerns the molecular basis of biological activity in and between cells, including molecular synthesis, modification, mechanisms and interactions.

Molecular Biologists design and perform experiments on molecules and cells to gain insight into how these components operate, organization, and communicate.Some clinical research and medical therapies arising from molecular biology are covered under gene therapy whereas the use of molecular biology or molecular cell biology in medicine is now referred to as molecular medicine. Molecular biology also plays important role in understanding formations, actions, and regulations of various parts of cells which can be used to efficiently target new drugs, diagnose disease, and understand the physiology of the cell.While molecular biology was established as an official branch of science in the 1930s, the term wasn't coined until 1938 by Warren Weaver. At the time, Weaver was the director of Natural Sciences for the Rockefeller Foundation and believed that biology was about to undergo significant change due to recent advancements in technology such as X-ray crystallography